HP 48G/GX darkened screen

[acoto]

Hello -

I have seen several HP 48G/GX with the center of the screen darkened. like this:



It seems to me that the liquid component diffuses over time on one of the glass plates.

It is curious that the corners do not seem affected.

Any way to fix it, but to replace the screen?

I am tempted to buy a damaged unit and start experimenting: heating, freezing... a dehumidifier.

[mfleming]

If you can see a faint outline of characters and icons when you turn it on, then the problem likely lies with the reflective backing behind the LCD glass, otherwise it's the LCD itself. Either way, you'll need to open the case and repair or replace the display. Replacement is the best option, though a recent member might be giving repair a try. The HP39G is a good candidate for replacement donor since it has a better contrast screen.

Have a look in the Articles forum and follow the link to the old article collection mentioned at the top to find several descriptions of the process. The process is a bit tough so you might want to practice on a dead 48 first. Alternatively there is someone in the US who will do the repair for you and you can find him on eBay, or scroll back a year or two through the Classified listings to find a post by him making the offer. The postage might be discouraging though!

When opening the case the "Charles Atlas" way, you need to watch out that you don't bend the keyboard plate as it will leave some of the lower keys feeling a bit mushy afterwards.

Read through and decide if you want to fix it yourself,
~Mark

[Jlouis]

High room temperature is the problem.

I have some 48 black LCD with the display like this. It happens in the summer in my city. Now I protect my calculators in conrolled temperature room, but in the past a mere 35°C toasted my 48 black LCD and a 49G.

Others calculators are prone to this problem also, like Pioneers and Voyagers, but at higher temperatures.

Interesting is that I never lost a 48 with blue LCD. Go figure.

Edit: I've noticed that you live in Costa Rica. I bet it's hot in your city in high summer, am I right? I live in Hell de Janeiro, Brazil

[mfleming]

Here is the link to repair information, last article in the current article list.

http://www.hpmuseum.org/forum/thread-49.html